text: /*
   * Copyright (c) 2009-2012, Salvatore Sanfilippo <antirez at gmail dot com>
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions are met:
   *
   *   * Redistributions of source code must retain the above copyright notice,
   *     this list of conditions and the following disclaimer.
   *   * Redistributions in binary form must reproduce the above copyright
   *     notice, this list of conditions and the following disclaimer in the
   *     documentation and/or other materials provided with the distribution.
   *   * Neither the name of Redis nor the names of its contributors may be used
   *     to endorse or promote products derived from this software without
   *     specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
   * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
   * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
   * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
   * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
   * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
   * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
   * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
   * POSSIBILITY OF SUCH DAMAGE.
   */
  
  #include "server.h"
  #include "sha1.h"   /* SHA1 is used for DEBUG DIGEST */
  #include "crc64.h"
  
  #include <arpa/inet.h>
  #include <signal.h>
  
  #ifdef HAVE_BACKTRACE
  #include <execinfo.h>
  #include <ucontext.h>
  #include <fcntl.h>
  #include "bio.h"
  #endif /* HAVE_BACKTRACE */
  
  #ifdef __CYGWIN__
  #ifndef SA_ONSTACK
  #define SA_ONSTACK 0x08000000
  #endif
  #endif
  
  /* ================================= Debugging ============================== */
  
  /* Compute the sha1 of string at 's' with 'len' bytes long.
   * The SHA1 is then xored against the string pointed by digest.
   * Since xor is commutative, this operation is used in order to
   * "add" digests relative to unordered elements.
   *
   * So digest(a,b,c,d) will be the same of digest(b,a,c,d) */
  void xorDigest(unsigned char *digest, void *ptr, size_t len) {
      SHA1_CTX ctx;
      unsigned char hash[20], *s = ptr;
      int j;
  
      SHA1Init(&ctx);
      SHA1Update(&ctx,s,len);
      SHA1Final(hash,&ctx);
  
      for (j = 0; j < 20; j++)
          digest[j] ^= hash[j];
  }
  
  void xorObjectDigest(unsigned char *digest, robj *o) {
      o = getDecodedObject(o);
      xorDigest(digest,o->ptr,sdslen(o->ptr));
      decrRefCount(o);
  }
  
  /* This function instead of just computing the SHA1 and xoring it
   * against digest, also perform the digest of "digest" itself and
   * replace the old value with the new one.
   *
   * So the final digest will be:
   *
   * digest = SHA1(digest xor SHA1(data))
   *
   * This function is used every time we want to preserve the order so
   * that digest(a,b,c,d) will be different than digest(b,c,d,a)
   *
   * Also note that mixdigest("foo") followed by mixdigest("bar")
   * will lead to a different digest compared to "fo", "obar".
   */
  void mixDigest(unsigned char *digest, void *ptr, size_t len) {
      SHA1_CTX ctx;
      char *s = ptr;
  
      xorDigest(digest,s,len);
      SHA1Init(&ctx);
      SHA1Update(&ctx,digest,20);
      SHA1Final(digest,&ctx);
  }
  
  void mixObjectDigest(unsigned char *digest, robj *o) {
      o = getDecodedObject(o);
      mixDigest(digest,o->ptr,sdslen(o->ptr));
      decrRefCount(o);
  }
  
  /* Compute the dataset digest. Since keys, sets elements, hashes elements
   * are not ordered, we use a trick: every aggregate digest is the xor
   * of the digests of their elements. This way the order will not change
   * the result. For list instead we use a feedback entering the output digest
   * as input in order to ensure that a different ordered list will result in
   * a different digest. */
  void computeDatasetDigest(unsigned char *final) {
      unsigned char digest[20];
      char buf[128];
      dictIterator *di = NULL;
      dictEntry *de;
      int j;
      uint32_t aux;
  
      memset(final,0,20); /* Start with a clean result */
  
      for (j = 0; j < server.dbnum; j++) {
          redisDb *db = server.db+j;
  
          if (dictSize(db->dict) == 0) continue;
          di = dictGetIterator(db->dict);
  
          /* hash the DB id, so the same dataset moved in a different
           * DB will lead to a different digest */
          aux = htonl(j);
          mixDigest(final,&aux,sizeof(aux));
  
          /* Iterate this DB writing every entry */
          while((de = dictNext(di)) != NULL) {
              sds key;
              robj *keyobj, *o;
              long long expiretime;
  
              memset(digest,0,20); /* This key-val digest */
              key = dictGetKey(de);
              keyobj = createStringObject(key,sdslen(key));
  
              mixDigest(digest,key,sdslen(key));
  
              o = dictGetVal(de);
  
              aux = htonl(o->type);
              mixDigest(digest,&aux,sizeof(aux));
              expiretime = getExpire(db,keyobj);
  
              /* Save the key and associated value */
              if (o->type == OBJ_STRING) {
                  mixObjectDigest(digest,o);
              } else if (o->type == OBJ_LIST) {
                  listTypeIterator *li = listTypeInitIterator(o,0,LIST_TAIL);
                  listTypeEntry entry;
                  while(listTypeNext(li,&entry)) {
                      robj *eleobj = listTypeGet(&entry);
                      mixObjectDigest(digest,eleobj);
                      decrRefCount(eleobj);
                  }
                  listTypeReleaseIterator(li);
              } else if (o->type == OBJ_SET) {
                  setTypeIterator *si = setTypeInitIterator(o);
                  sds sdsele;
                  while((sdsele = setTypeNextObject(si)) != NULL) {
                      xorDigest(digest,sdsele,sdslen(sdsele));
                      sdsfree(sdsele);
                  }
                  setTypeReleaseIterator(si);
              } else if (o->type == OBJ_ZSET) {
                  unsigned char eledigest[20];
  
                  if (o->encoding == OBJ_ENCODING_ZIPLIST) {
                      unsigned char *zl = o->ptr;
                      unsigned char *eptr, *sptr;
                      unsigned char *vstr;
                      unsigned int vlen;
                      long long vll;
                      double score;
  
                      eptr = ziplistIndex(zl,0);
                      serverAssert(eptr != NULL);
                      sptr = ziplistNext(zl,eptr);
                      serverAssert(sptr != NULL);
  
                      while (eptr != NULL) {
                          serverAssert(ziplistGet(eptr,&vstr,&vlen,&vll));
                          score = zzlGetScore(sptr);
  
                          memset(eledigest,0,20);
                          if (vstr != NULL) {
                              mixDigest(eledigest,vstr,vlen);
                          } else {
                              ll2string(buf,sizeof(buf),vll);
                              mixDigest(eledigest,buf,strlen(buf));
                          }
  
                          snprintf(buf,sizeof(buf),"%.17g",score);
                          mixDigest(eledigest,buf,strlen(buf));
                          xorDigest(digest,eledigest,20);
                          zzlNext(zl,&eptr,&sptr);
                      }
                  } else if (o->encoding == OBJ_ENCODING_SKIPLIST) {
                      zset *zs = o->ptr;
                      dictIterator *di = dictGetIterator(zs->dict);
                      dictEntry *de;
  
                      while((de = dictNext(di)) != NULL) {
                          sds sdsele = dictGetKey(de);
                          double *score = dictGetVal(de);
  
                          snprintf(buf,sizeof(buf),"%.17g",*score);
                          memset(eledigest,0,20);
                          mixDigest(eledigest,sdsele,sdslen(sdsele));
                          mixDigest(eledigest,buf,strlen(buf));
                          xorDigest(digest,eledigest,20);
                      }
                      dictReleaseIterator(di);
                  } else {
                      serverPanic("Unknown sorted set encoding");
                  }
              } else if (o->type == OBJ_HASH) {
                  hashTypeIterator *hi = hashTypeInitIterator(o);
                  while (hashTypeNext(hi) != C_ERR) {
                      unsigned char eledigest[20];
                      sds sdsele;
  
                      memset(eledigest,0,20);
                      sdsele = hashTypeCurrentObjectNewSds(hi,OBJ_HASH_KEY);
                      mixDigest(eledigest,sdsele,sdslen(sdsele));
                      sdsfree(sdsele);
                      sdsele = hashTypeCurrentObjectNewSds(hi,OBJ_HASH_VALUE);
                      mixDigest(eledigest,sdsele,sdslen(sdsele));
                      sdsfree(sdsele);
                      xorDigest(digest,eledigest,20);
                  }
                  hashTypeReleaseIterator(hi);
              } else {
                  serverPanic("Unknown object type");
              }
              /* If the key has an expire, add it to the mix */
              if (expiretime != -1) xorDigest(digest,"!!expire!!",10);
              /* We can finally xor the key-val digest to the final digest */
              xorDigest(final,digest,20);
              decrRefCount(keyobj);
          }
          dictReleaseIterator(di);
      }
  }
  
  void inputCatSds(void *result, const char *str) {
      /* result is actually a (sds *), so re-cast it here */
      sds *info = (sds *)result;
      *info = sdscat(*info, str);
  }
  
  void debugCommand(client *c) {
      if (!strcasecmp(c->argv[1]->ptr,"segfault")) {
          *((char*)-1) = 'x';
      } else if (!strcasecmp(c->argv[1]->ptr,"restart") ||
                 !strcasecmp(c->argv[1]->ptr,"crash-and-recover"))
      {
          long long delay = 0;
          if (c->argc >= 3) {
              if (getLongLongFromObjectOrReply(c, c->argv[2], &delay, NULL)
                  != C_OK) return;
              if (delay < 0) delay = 0;
          }
          int flags = !strcasecmp(c->argv[1]->ptr,"restart") ?
              (RESTART_SERVER_GRACEFULLY|RESTART_SERVER_CONFIG_REWRITE) :
               RESTART_SERVER_NONE;
          restartServer(flags,delay);
          addReplyError(c,"failed to restart the server. Check server logs.");
      } else if (!strcasecmp(c->argv[1]->ptr,"oom")) {
          void *ptr = zmalloc(ULONG_MAX); /* Should trigger an out of memory. */
          zfree(ptr);
          addReply(c,shared.ok);
      } else if (!strcasecmp(c->argv[1]->ptr,"assert")) {
          if (c->argc >= 3) c->argv[2] = tryObjectEncoding(c->argv[2]);
          serverAssertWithInfo(c,c->argv[0],1 == 2);
      } else if (!strcasecmp(c->argv[1]->ptr,"reload")) {
          if (rdbSave(server.rdb_filename) != C_OK) {
              addReply(c,shared.err);
              return;
          }
          emptyDb(-1,EMPTYDB_NO_FLAGS,NULL);
          if (rdbLoad(server.rdb_filename) != C_OK) {
              addReplyError(c,"Error trying to load the RDB dump");
              return;
          }
          serverLog(LL_WARNING,"DB reloaded by DEBUG RELOAD");
          addReply(c,shared.ok);
      } else if (!strcasecmp(c->argv[1]->ptr,"loadaof")) {
          if (server.aof_state == AOF_ON) flushAppendOnlyFile(1);
          emptyDb(-1,EMPTYDB_NO_FLAGS,NULL);
          if (loadAppendOnlyFile(server.aof_filename) != C_OK) {
              addReply(c,shared.err);
              return;
          }
          server.dirty = 0; /* Prevent AOF / replication */
          serverLog(LL_WARNING,"Append Only File loaded by DEBUG LOADAOF");
          addReply(c,shared.ok);
      } else if (!strcasecmp(c->argv[1]->ptr,"object") && c->argc == 3) {
          dictEntry *de;
          robj *val;
          char *strenc;
  
          if ((de = dictFind(c->db->dict,c->argv[2]->ptr)) == NULL) {
              addReply(c,shared.nokeyerr);
              return;
          }
          val = dictGetVal(de);
          strenc = strEncoding(val->encoding);
  
          char extra[128] = {0};
          if (val->encoding == OBJ_ENCODING_QUICKLIST) {
              char *nextra = extra;
              int remaining = sizeof(extra);
              quicklist *ql = val->ptr;
              /* Add number of quicklist nodes */
              int used = snprintf(nextra, remaining, " ql_nodes:%u", ql->len);
              nextra += used;
              remaining -= used;
              /* Add average quicklist fill factor */
              double avg = (double)ql->count/ql->len;
              used = snprintf(nextra, remaining, " ql_avg_node:%.2f", avg);
              nextra += used;
              remaining -= used;
              /* Add quicklist fill level / max ziplist size */
              used = snprintf(nextra, remaining, " ql_ziplist_max:%d", ql->fill);
              nextra += used;
              remaining -= used;
              /* Add isCompressed? */
              int compressed = ql->compress != 0;
              used = snprintf(nextra, remaining, " ql_compressed:%d", compressed);
              nextra += used;
              remaining -= used;
              /* Add total uncompressed size */
              unsigned long sz = 0;
              for (quicklistNode *node = ql->head; node; node = node->next) {
                  sz += node->sz;
              }
              used = snprintf(nextra, remaining, " ql_uncompressed_size:%lu", sz);
              nextra += used;
              remaining -= used;
          }
  
          addReplyStatusFormat(c,
              "Value at:%p refcount:%d "
              "encoding:%s serializedlength:%zu "
              "lru:%d lru_seconds_idle:%llu%s",
              (void*)val, val->refcount,
              strenc, rdbSavedObjectLen(val),
              val->lru, estimateObjectIdleTime(val)/1000, extra);
      } else if (!strcasecmp(c->argv[1]->ptr,"sdslen") && c->argc == 3) {
          dictEntry *de;
          robj *val;
          sds key;
  
          if ((de = dictFind(c->db->dict,c->argv[2]->ptr)) == NULL) {
              addReply(c,shared.nokeyerr);
              return;
          }
          val = dictGetVal(de);
          key = dictGetKey(de);
  
          if (val->type != OBJ_STRING || !sdsEncodedObject(val)) {
              addReplyError(c,"Not an sds encoded string.");
          } else {
              addReplyStatusFormat(c,
                  "key_sds_len:%lld, key_sds_avail:%lld, "
                  "val_sds_len:%lld, val_sds_avail:%lld",
                  (long long) sdslen(key),
                  (long long) sdsavail(key),
                  (long long) sdslen(val->ptr),
                  (long long) sdsavail(val->ptr));
          }
      } else if (!strcasecmp(c->argv[1]->ptr,"populate") &&
                 (c->argc == 3 || c->argc == 4)) {
          long keys, j;
          robj *key, *val;
          char buf[128];
  
          if (getLongFromObjectOrReply(c, c->argv[2], &keys, NULL) != C_OK)
              return;
          dictExpand(c->db->dict,keys);
          for (j = 0; j < keys; j++) {
              snprintf(buf,sizeof(buf),"%s:%lu",
                  (c->argc == 3) ? "key" : (char*)c->argv[3]->ptr, j);
              key = createStringObject(buf,strlen(buf));
              if (lookupKeyWrite(c->db,key) != NULL) {
                  decrRefCount(key);
                  continue;
              }
              snprintf(buf,sizeof(buf),"value:%lu",j);
              val = createStringObject(buf,strlen(buf));
              dbAdd(c->db,key,val);
              decrRefCount(key);
          }
          addReply(c,shared.ok);
      } else if (!strcasecmp(c->argv[1]->ptr,"digest") && c->argc == 2) {
          unsigned char digest[20];
          sds d = sdsempty();
          int j;
  
          computeDatasetDigest(digest);
          for (j = 0; j < 20; j++)
              d = sdscatprintf(d, "%02x",digest[j]);
          addReplyStatus(c,d);
          sdsfree(d);
      } else if (!strcasecmp(c->argv[1]->ptr,"sleep") && c->argc == 3) {
          double dtime = strtod(c->argv[2]->ptr,NULL);
          long long utime = dtime*1000000;
          struct timespec tv;
  
          tv.tv_sec = utime / 1000000;
          tv.tv_nsec = (utime % 1000000) * 1000;
          nanosleep(&tv, NULL);
          addReply(c,shared.ok);
      } else if (!strcasecmp(c->argv[1]->ptr,"set-active-expire") &&
                 c->argc == 3)
      {
          server.active_expire_enabled = atoi(c->argv[2]->ptr);
          addReply(c,shared.ok);
      } else if (!strcasecmp(c->argv[1]->ptr,"lua-always-replicate-commands") &&
                 c->argc == 3)
      {
          server.lua_always_replicate_commands = atoi(c->argv[2]->ptr);
          addReply(c,shared.ok);
      } else if (!strcasecmp(c->argv[1]->ptr,"error") && c->argc == 3) {
          sds errstr = sdsnewlen("-",1);
  
          errstr = sdscatsds(errstr,c->argv[2]->ptr);
          errstr = sdsmapchars(errstr,"\n\r","  ",2); /* no newlines in errors. */
          errstr = sdscatlen(errstr,"\r\n",2);
          addReplySds(c,errstr);
      } else if (!strcasecmp(c->argv[1]->ptr,"structsize") && c->argc == 2) {
          sds sizes = sdsempty();
          sizes = sdscatprintf(sizes,"bits:%d ",(sizeof(void*) == 8)?64:32);
          sizes = sdscatprintf(sizes,"robj:%d ",(int)sizeof(robj));
          sizes = sdscatprintf(sizes,"dictentry:%d ",(int)sizeof(dictEntry));
          sizes = sdscatprintf(sizes,"sdshdr5:%d ",(int)sizeof(struct sdshdr5));
          sizes = sdscatprintf(sizes,"sdshdr8:%d ",(int)sizeof(struct sdshdr8));
          sizes = sdscatprintf(sizes,"sdshdr16:%d ",(int)sizeof(struct sdshdr16));
          sizes = sdscatprintf(sizes,"sdshdr32:%d ",(int)sizeof(struct sdshdr32));
          sizes = sdscatprintf(sizes,"sdshdr64:%d ",(int)sizeof(struct sdshdr64));
          addReplyBulkSds(c,sizes);
      } else if (!strcasecmp(c->argv[1]->ptr,"htstats") && c->argc == 3) {
          long dbid;
          sds stats = sdsempty();
          char buf[4096];
  
          if (getLongFromObjectOrReply(c, c->argv[2], &dbid, NULL) != C_OK)
              return;
          if (dbid < 0 || dbid >= server.dbnum) {
              addReplyError(c,"Out of range database");
              return;
          }
  
          stats = sdscatprintf(stats,"[Dictionary HT]\n");
          dictGetStats(buf,sizeof(buf),server.db[dbid].dict);
          stats = sdscat(stats,buf);
  
          stats = sdscatprintf(stats,"[Expires HT]\n");
          dictGetStats(buf,sizeof(buf),server.db[dbid].expires);
          stats = sdscat(stats,buf);
  
          addReplyBulkSds(c,stats);
      } else if (!strcasecmp(c->argv[1]->ptr,"jemalloc") && c->argc == 3) {
  #if defined(USE_JEMALLOC)
          if (!strcasecmp(c->argv[2]->ptr, "info")) {
              sds info = sdsempty();
              je_malloc_stats_print(inputCatSds, &info, NULL);
              addReplyBulkSds(c, info);
          } else {
              addReplyErrorFormat(c, "Valid jemalloc debug fields: info");
          }
  #else
          addReplyErrorFormat(c, "jemalloc support not available");
  #endif
      } else {
          addReplyErrorFormat(c, "Unknown DEBUG subcommand or wrong number of arguments for '%s'",
              (char*)c->argv[1]->ptr);
      }
  }
  
  /* =========================== Crash handling  ============================== */
  
  void _serverAssert(char *estr, char *file, int line) {
      bugReportStart();
      serverLog(LL_WARNING,"=== ASSERTION FAILED ===");
      serverLog(LL_WARNING,"==> %s:%d '%s' is not true",file,line,estr);
  #ifdef HAVE_BACKTRACE
      server.assert_failed = estr;
      server.assert_file = file;
      server.assert_line = line;
      serverLog(LL_WARNING,"(forcing SIGSEGV to print the bug report.)");
  #endif
      *((char*)-1) = 'x';
  }
  
  void _serverAssertPrintClientInfo(client *c) {
      int j;
  
      bugReportStart();
      serverLog(LL_WARNING,"=== ASSERTION FAILED CLIENT CONTEXT ===");
      serverLog(LL_WARNING,"client->flags = %d", c->flags);
      serverLog(LL_WARNING,"client->fd = %d", c->fd);
      serverLog(LL_WARNING,"client->argc = %d", c->argc);
      for (j=0; j < c->argc; j++) {
          char buf[128];
          char *arg;
  
          if (c->argv[j]->type == OBJ_STRING && sdsEncodedObject(c->argv[j])) {
              arg = (char*) c->argv[j]->ptr;
          } else {
              snprintf(buf,sizeof(buf),"Object type: %d, encoding: %d",
                  c->argv[j]->type, c->argv[j]->encoding);
              arg = buf;
          }
          serverLog(LL_WARNING,"client->argv[%d] = \"%s\" (refcount: %d)",
              j, arg, c->argv[j]->refcount);
      }
  }
  
  void serverLogObjectDebugInfo(robj *o) {
      serverLog(LL_WARNING,"Object type: %d", o->type);
      serverLog(LL_WARNING,"Object encoding: %d", o->encoding);
      serverLog(LL_WARNING,"Object refcount: %d", o->refcount);
      if (o->type == OBJ_STRING && sdsEncodedObject(o)) {
          serverLog(LL_WARNING,"Object raw string len: %zu", sdslen(o->ptr));
          if (sdslen(o->ptr) < 4096) {
              sds repr = sdscatrepr(sdsempty(),o->ptr,sdslen(o->ptr));
              serverLog(LL_WARNING,"Object raw string content: %s", repr);
              sdsfree(repr);
          }
      } else if (o->type == OBJ_LIST) {
          serverLog(LL_WARNING,"List length: %d", (int) listTypeLength(o));
      } else if (o->type == OBJ_SET) {
          serverLog(LL_WARNING,"Set size: %d", (int) setTypeSize(o));
      } else if (o->type == OBJ_HASH) {
          serverLog(LL_WARNING,"Hash size: %d", (int) hashTypeLength(o));
      } else if (o->type == OBJ_ZSET) {
          serverLog(LL_WARNING,"Sorted set size: %d", (int) zsetLength(o));
          if (o->encoding == OBJ_ENCODING_SKIPLIST)
              serverLog(LL_WARNING,"Skiplist level: %d", (int) ((zset*)o->ptr)->zsl->level);
      }
  }
  
  void _serverAssertPrintObject(robj *o) {
      bugReportStart();
      serverLog(LL_WARNING,"=== ASSERTION FAILED OBJECT CONTEXT ===");
      serverLogObjectDebugInfo(o);
  }
  
  void _serverAssertWithInfo(client *c, robj *o, char *estr, char *file, int line) {
      if (c) _serverAssertPrintClientInfo(c);
      if (o) _serverAssertPrintObject(o);
      _serverAssert(estr,file,line);
  }
  
  void _serverPanic(char *msg, char *file, int line) {
      bugReportStart();
      serverLog(LL_WARNING,"------------------------------------------------");
      serverLog(LL_WARNING,"!!! Software Failure. Press left mouse button to continue");
      serverLog(LL_WARNING,"Guru Meditation: %s #%s:%d",msg,file,line);
  #ifdef HAVE_BACKTRACE
      serverLog(LL_WARNING,"(forcing SIGSEGV in order to print the stack trace)");
  #endif
      serverLog(LL_WARNING,"------------------------------------------------");
      *((char*)-1) = 'x';
  }
  
  void bugReportStart(void) {
      if (server.bug_report_start == 0) {
          serverLog(LL_WARNING,
              "\n\n=== REDIS BUG REPORT START: Cut & paste starting from here ===");
          server.bug_report_start = 1;
      }
  }
  
  #ifdef HAVE_BACKTRACE
  static void *getMcontextEip(ucontext_t *uc) {
  #if defined(__APPLE__) && !defined(MAC_OS_X_VERSION_10_6)
      /* OSX < 10.6 */
      #if defined(__x86_64__)
      return (void*) uc->uc_mcontext->__ss.__rip;
      #elif defined(__i386__)
      return (void*) uc->uc_mcontext->__ss.__eip;
      #else
      return (void*) uc->uc_mcontext->__ss.__srr0;
      #endif
  #elif defined(__APPLE__) && defined(MAC_OS_X_VERSION_10_6)
      /* OSX >= 10.6 */
      #if defined(_STRUCT_X86_THREAD_STATE64) && !defined(__i386__)
      return (void*) uc->uc_mcontext->__ss.__rip;
      #else
      return (void*) uc->uc_mcontext->__ss.__eip;
      #endif
  #elif defined(__linux__)
      /* Linux */
      #if defined(__i386__)
      return (void*) uc->uc_mcontext.gregs[14]; /* Linux 32 */
      #elif defined(__X86_64__) || defined(__x86_64__)
      return (void*) uc->uc_mcontext.gregs[16]; /* Linux 64 */
      #elif defined(__ia64__) /* Linux IA64 */
      return (void*) uc->uc_mcontext.sc_ip;
      #endif
  #else
      return NULL;
  #endif
  }
  
  void logStackContent(void **sp) {
      int i;
      for (i = 15; i >= 0; i--) {
          unsigned long addr = (unsigned long) sp+i;
          unsigned long val = (unsigned long) sp[i];
  
          if (sizeof(long) == 4)
              serverLog(LL_WARNING, "(%08lx) -> %08lx", addr, val);
          else
              serverLog(LL_WARNING, "(%016lx) -> %016lx", addr, val);
      }
  }
  
  void logRegisters(ucontext_t *uc) {
      serverLog(LL_WARNING, "--- REGISTERS");
  
  /* OSX */
  #if defined(__APPLE__) && defined(MAC_OS_X_VERSION_10_6)
    /* OSX AMD64 */
      #if defined(_STRUCT_X86_THREAD_STATE64) && !defined(__i386__)
      serverLog(LL_WARNING,
      "\n"
      "RAX:%016lx RBX:%016lx\nRCX:%016lx RDX:%016lx\n"
      "RDI:%016lx RSI:%016lx\nRBP:%016lx RSP:%016lx\n"
      "R8 :%016lx R9 :%016lx\nR10:%016lx R11:%016lx\n"
      "R12:%016lx R13:%016lx\nR14:%016lx R15:%016lx\n"
      "RIP:%016lx EFL:%016lx\nCS :%016lx FS:%016lx  GS:%016lx",
          (unsigned long) uc->uc_mcontext->__ss.__rax,
          (unsigned long) uc->uc_mcontext->__ss.__rbx,
          (unsigned long) uc->uc_mcontext->__ss.__rcx,
          (unsigned long) uc->uc_mcontext->__ss.__rdx,
          (unsigned long) uc->uc_mcontext->__ss.__rdi,
          (unsigned long) uc->uc_mcontext->__ss.__rsi,
          (unsigned long) uc->uc_mcontext->__ss.__rbp,
          (unsigned long) uc->uc_mcontext->__ss.__rsp,
          (unsigned long) uc->uc_mcontext->__ss.__r8,
          (unsigned long) uc->uc_mcontext->__ss.__r9,
          (unsigned long) uc->uc_mcontext->__ss.__r10,
          (unsigned long) uc->uc_mcontext->__ss.__r11,
          (unsigned long) uc->uc_mcontext->__ss.__r12,
          (unsigned long) uc->uc_mcontext->__ss.__r13,
          (unsigned long) uc->uc_mcontext->__ss.__r14,
          (unsigned long) uc->uc_mcontext->__ss.__r15,
          (unsigned long) uc->uc_mcontext->__ss.__rip,
          (unsigned long) uc->uc_mcontext->__ss.__rflags,
          (unsigned long) uc->uc_mcontext->__ss.__cs,
          (unsigned long) uc->uc_mcontext->__ss.__fs,
          (unsigned long) uc->uc_mcontext->__ss.__gs
      );
      logStackContent((void**)uc->uc_mcontext->__ss.__rsp);
      #else
      /* OSX x86 */
      serverLog(LL_WARNING,
      "\n"
      "EAX:%08lx EBX:%08lx ECX:%08lx EDX:%08lx\n"
      "EDI:%08lx ESI:%08lx EBP:%08lx ESP:%08lx\n"
      "SS:%08lx  EFL:%08lx EIP:%08lx CS :%08lx\n"
      "DS:%08lx  ES:%08lx  FS :%08lx GS :%08lx",
          (unsigned long) uc->uc_mcontext->__ss.__eax,
          (unsigned long) uc->uc_mcontext->__ss.__ebx,
          (unsigned long) uc->uc_mcontext->__ss.__ecx,
          (unsigned long) uc->uc_mcontext->__ss.__edx,
          (unsigned long) uc->uc_mcontext->__ss.__edi,
          (unsigned long) uc->uc_mcontext->__ss.__esi,
          (unsigned long) uc->uc_mcontext->__ss.__ebp,
          (unsigned long) uc->uc_mcontext->__ss.__esp,
          (unsigned long) uc->uc_mcontext->__ss.__ss,
          (unsigned long) uc->uc_mcontext->__ss.__eflags,
          (unsigned long) uc->uc_mcontext->__ss.__eip,
          (unsigned long) uc->uc_mcontext->__ss.__cs,
          (unsigned long) uc->uc_mcontext->__ss.__ds,
          (unsigned long) uc->uc_mcontext->__ss.__es,
          (unsigned long) uc->uc_mcontext->__ss.__fs,
          (unsigned long) uc->uc_mcontext->__ss.__gs
      );
      logStackContent((void**)uc->uc_mcontext->__ss.__esp);
      #endif
  /* Linux */
  #elif defined(__linux__)
      /* Linux x86 */
      #if defined(__i386__)
      serverLog(LL_WARNING,
      "\n"
      "EAX:%08lx EBX:%08lx ECX:%08lx EDX:%08lx\n"
      "EDI:%08lx ESI:%08lx EBP:%08lx ESP:%08lx\n"
      "SS :%08lx EFL:%08lx EIP:%08lx CS:%08lx\n"
      "DS :%08lx ES :%08lx FS :%08lx GS:%08lx",
          (unsigned long) uc->uc_mcontext.gregs[11],
          (unsigned long) uc->uc_mcontext.gregs[8],
          (unsigned long) uc->uc_mcontext.gregs[10],
          (unsigned long) uc->uc_mcontext.gregs[9],
          (unsigned long) uc->uc_mcontext.gregs[4],
          (unsigned long) uc->uc_mcontext.gregs[5],
          (unsigned long) uc->uc_mcontext.gregs[6],
          (unsigned long) uc->uc_mcontext.gregs[7],
          (unsigned long) uc->uc_mcontext.gregs[18],
          (unsigned long) uc->uc_mcontext.gregs[17],
          (unsigned long) uc->uc_mcontext.gregs[14],
          (unsigned long) uc->uc_mcontext.gregs[15],
          (unsigned long) uc->uc_mcontext.gregs[3],
          (unsigned long) uc->uc_mcontext.gregs[2],
          (unsigned long) uc->uc_mcontext.gregs[1],
          (unsigned long) uc->uc_mcontext.gregs[0]
      );
      logStackContent((void**)uc->uc_mcontext.gregs[7]);
      #elif defined(__X86_64__) || defined(__x86_64__)
      /* Linux AMD64 */
      serverLog(LL_WARNING,
      "\n"
      "RAX:%016lx RBX:%016lx\nRCX:%016lx RDX:%016lx\n"
      "RDI:%016lx RSI:%016lx\nRBP:%016lx RSP:%016lx\n"
      "R8 :%016lx R9 :%016lx\nR10:%016lx R11:%016lx\n"
      "R12:%016lx R13:%016lx\nR14:%016lx R15:%016lx\n"
      "RIP:%016lx EFL:%016lx\nCSGSFS:%016lx",
          (unsigned long) uc->uc_mcontext.gregs[13],
          (unsigned long) uc->uc_mcontext.gregs[11],
          (unsigned long) uc->uc_mcontext.gregs[14],
          (unsigned long) uc->uc_mcontext.gregs[12],
          (unsigned long) uc->uc_mcontext.gregs[8],
          (unsigned long) uc->uc_mcontext.gregs[9],
          (unsigned long) uc->uc_mcontext.gregs[10],
          (unsigned long) uc->uc_mcontext.gregs[15],
          (unsigned long) uc->uc_mcontext.gregs[0],
          (unsigned long) uc->uc_mcontext.gregs[1],
          (unsigned long) uc->uc_mcontext.gregs[2],
          (unsigned long) uc->uc_mcontext.gregs[3],
          (unsigned long) uc->uc_mcontext.gregs[4],
          (unsigned long) uc->uc_mcontext.gregs[5],
          (unsigned long) uc->uc_mcontext.gregs[6],
          (unsigned long) uc->uc_mcontext.gregs[7],
          (unsigned long) uc->uc_mcontext.gregs[16],
          (unsigned long) uc->uc_mcontext.gregs[17],
          (unsigned long) uc->uc_mcontext.gregs[18]
      );
      logStackContent((void**)uc->uc_mcontext.gregs[15]);
      #endif
  #else
      serverLog(LL_WARNING,
          "  Dumping of registers not supported for this OS/arch");
  #endif
  }
  
  /* Logs the stack trace using the backtrace() call. This function is designed
   * to be called from signal handlers safely. */
  void logStackTrace(ucontext_t *uc) {
      void *trace[100];
      int trace_size = 0, fd;
      int log_to_stdout = server.logfile[0] == '\0';
  
      /* Open the log file in append mode. */
      fd = log_to_stdout ?
          STDOUT_FILENO :
          open(server.logfile, O_APPEND|O_CREAT|O_WRONLY, 0644);
      if (fd == -1) return;
  
      /* Generate the stack trace */
      trace_size = backtrace(trace, 100);
  
      /* overwrite sigaction with caller's address */
      if (getMcontextEip(uc) != NULL)
          trace[1] = getMcontextEip(uc);
  
      /* Write symbols to log file */
      backtrace_symbols_fd(trace, trace_size, fd);
  
      /* Cleanup */
      if (!log_to_stdout) close(fd);
  }
  
  /* Log information about the "current" client, that is, the client that is
   * currently being served by Redis. May be NULL if Redis is not serving a
   * client right now. */
  void logCurrentClient(void) {
      if (server.current_client == NULL) return;
  
      client *cc = server.current_client;
      sds client;
      int j;
  
      serverLog(LL_WARNING, "--- CURRENT CLIENT INFO");
      client = catClientInfoString(sdsempty(),cc);
      serverLog(LL_WARNING,"client: %s", client);
      sdsfree(client);
      for (j = 0; j < cc->argc; j++) {
          robj *decoded;
  
          decoded = getDecodedObject(cc->argv[j]);
          serverLog(LL_WARNING,"argv[%d]: '%s'", j, (char*)decoded->ptr);
          decrRefCount(decoded);
      }
      /* Check if the first argument, usually a key, is found inside the
       * selected DB, and if so print info about the associated object. */
      if (cc->argc >= 1) {
          robj *val, *key;
          dictEntry *de;
  
          key = getDecodedObject(cc->argv[1]);
          de = dictFind(cc->db->dict, key->ptr);
          if (de) {
              val = dictGetVal(de);
              serverLog(LL_WARNING,"key '%s' found in DB containing the following object:", (char*)key->ptr);
              serverLogObjectDebugInfo(val);
          }
          decrRefCount(key);
      }
  }
  
  #if defined(HAVE_PROC_MAPS)
  void memtest_non_destructive_invert(void *addr, size_t size);
  void memtest_non_destructive_swap(void *addr, size_t size);
  #define MEMTEST_MAX_REGIONS 128
  
  int memtest_test_linux_anonymous_maps(void) {
      FILE *fp = fopen("/proc/self/maps","r");
      char line[1024];
      size_t start_addr, end_addr, size;
      size_t start_vect[MEMTEST_MAX_REGIONS];
      size_t size_vect[MEMTEST_MAX_REGIONS];
      int regions = 0, j;
      uint64_t crc1 = 0, crc2 = 0, crc3 = 0;
  
      while(fgets(line,sizeof(line),fp) != NULL) {
          char *start, *end, *p = line;
  
          start = p;
          p = strchr(p,'-');
          if (!p) continue;
          *p++ = '\0';
          end = p;
          p = strchr(p,' ');
          if (!p) continue;
          *p++ = '\0';
          if (strstr(p,"stack") ||
              strstr(p,"vdso") ||
              strstr(p,"vsyscall")) continue;
          if (!strstr(p,"00:00")) continue;
          if (!strstr(p,"rw")) continue;
  
          start_addr = strtoul(start,NULL,16);
          end_addr = strtoul(end,NULL,16);
          size = end_addr-start_addr;
  
          start_vect[regions] = start_addr;
          size_vect[regions] = size;
          printf("Testing %lx %lu\n", (unsigned long) start_vect[regions],
                                      (unsigned long) size_vect[regions]);
          regions++;
      }
  
      /* Test all the regions as an unique sequential region.
       * 1) Take the CRC64 of the memory region. */
      for (j = 0; j < regions; j++) {
          crc1 = crc64(crc1,(void*)start_vect[j],size_vect[j]);
      }
  
      /* 2) Invert bits, swap adjacent words, swap again, invert bits.
       * This is the error amplification step. */
      for (j = 0; j < regions; j++)
          memtest_non_destructive_invert((void*)start_vect[j],size_vect[j]);
      for (j = 0; j < regions; j++)
          memtest_non_destructive_swap((void*)start_vect[j],size_vect[j]);
      for (j = 0; j < regions; j++)
          memtest_non_destructive_swap((void*)start_vect[j],size_vect[j]);
      for (j = 0; j < regions; j++)
          memtest_non_destructive_invert((void*)start_vect[j],size_vect[j]);
  
      /* 3) Take the CRC64 sum again. */
      for (j = 0; j < regions; j++)
          crc2 = crc64(crc2,(void*)start_vect[j],size_vect[j]);
  
      /* 4) Swap + Swap again */
      for (j = 0; j < regions; j++)
          memtest_non_destructive_swap((void*)start_vect[j],size_vect[j]);
      for (j = 0; j < regions; j++)
          memtest_non_destructive_swap((void*)start_vect[j],size_vect[j]);
  
      /* 5) Take the CRC64 sum again. */
      for (j = 0; j < regions; j++)
          crc3 = crc64(crc3,(void*)start_vect[j],size_vect[j]);
  
      /* NOTE: It is very important to close the file descriptor only now
       * because closing it before may result into unmapping of some memory
       * region that we are testing. */
      fclose(fp);
  
      /* If the two CRC are not the same, we trapped a memory error. */
      return crc1 != crc2 || crc2 != crc3;
  }
  #endif
  
  void sigsegvHandler(int sig, siginfo_t *info, void *secret) {
      ucontext_t *uc = (ucontext_t*) secret;
      sds infostring, clients;
      struct sigaction act;
      UNUSED(info);
  
      bugReportStart();
      serverLog(LL_WARNING,
          "    Redis %s crashed by signal: %d", REDIS_VERSION, sig);
      serverLog(LL_WARNING,
          "    Failed assertion: %s (%s:%d)", server.assert_failed,
                          server.assert_file, server.assert_line);
  
      /* Log the stack trace */
      serverLog(LL_WARNING, "--- STACK TRACE");
      logStackTrace(uc);
  
      /* Log INFO and CLIENT LIST */
      serverLog(LL_WARNING, "--- INFO OUTPUT");
      infostring = genRedisInfoString("all");
      infostring = sdscatprintf(infostring, "hash_init_value: %u\n",
          dictGetHashFunctionSeed());
      serverLogRaw(LL_WARNING, infostring);
      serverLog(LL_WARNING, "--- CLIENT LIST OUTPUT");
      clients = getAllClientsInfoString();
      serverLogRaw(LL_WARNING, clients);
      sdsfree(infostring);
      sdsfree(clients);
  
      /* Log the current client */
      logCurrentClient();
  
      /* Log dump of processor registers */
      logRegisters(uc);
  
  #if defined(HAVE_PROC_MAPS)
      /* Test memory */
      serverLog(LL_WARNING, "--- FAST MEMORY TEST");
      bioKillThreads();
      if (memtest_test_linux_anonymous_maps()) {
          serverLog(LL_WARNING,
              "!!! MEMORY ERROR DETECTED! Check your memory ASAP !!!");
      } else {
          serverLog(LL_WARNING,
              "Fast memory test PASSED, however your memory can still be broken. Please run a memory test for several hours if possible.");
      }
  #endif
  
      serverLog(LL_WARNING,
  "\n=== REDIS BUG REPORT END. Make sure to include from START to END. ===\n\n"
  "       Please report the crash by opening an issue on github:\n\n"
  "           http://github.com/antirez/redis/issues\n\n"
  "  Suspect RAM error? Use redis-server --test-memory to verify it.\n\n"
  );
      /* free(messages); Don't call free() with possibly corrupted memory. */
      if (server.daemonize && server.supervised == 0) unlink(server.pidfile);
  
      /* Make sure we exit with the right signal at the end. So for instance
       * the core will be dumped if enabled. */
      sigemptyset (&act.sa_mask);
      act.sa_flags = SA_NODEFER | SA_ONSTACK | SA_RESETHAND;
      act.sa_handler = SIG_DFL;
      sigaction (sig, &act, NULL);
      kill(getpid(),sig);
  }
  #endif /* HAVE_BACKTRACE */
  
  /* ==================== Logging functions for debugging ===================== */
  
  void serverLogHexDump(int level, char *descr, void *value, size_t len) {
      char buf[65], *b;
      unsigned char *v = value;
      char charset[] = "0123456789abcdef";
  
      serverLog(level,"%s (hexdump):", descr);
      b = buf;
      while(len) {
          b[0] = charset[(*v)>>4];
          b[1] = charset[(*v)&0xf];
          b[2] = '\0';
          b += 2;
          len--;
          v++;
          if (b-buf == 64 || len == 0) {
              serverLogRaw(level|LL_RAW,buf);
              b = buf;
          }
      }
      serverLogRaw(level|LL_RAW,"\n");
  }
  
  /* =========================== Software Watchdog ============================ */
  #include <sys/time.h>
  
  void watchdogSignalHandler(int sig, siginfo_t *info, void *secret) {
  #ifdef HAVE_BACKTRACE
      ucontext_t *uc = (ucontext_t*) secret;
  #endif
      UNUSED(info);
      UNUSED(sig);
  
      serverLogFromHandler(LL_WARNING,"\n--- WATCHDOG TIMER EXPIRED ---");
  #ifdef HAVE_BACKTRACE
      logStackTrace(uc);
  #else
      serverLogFromHandler(LL_WARNING,"Sorry: no support for backtrace().");
  #endif
      serverLogFromHandler(LL_WARNING,"--------\n");
  }
  
  /* Schedule a SIGALRM delivery after the specified period in milliseconds.
   * If a timer is already scheduled, this function will re-schedule it to the
   * specified time. If period is 0 the current timer is disabled. */
  void watchdogScheduleSignal(int period) {
      struct itimerval it;
  
      /* Will stop the timer if period is 0. */
      it.it_value.tv_sec = period/1000;
      it.it_value.tv_usec = (period%1000)*1000;
      /* Don't automatically restart. */
      it.it_interval.tv_sec = 0;
      it.it_interval.tv_usec = 0;
      setitimer(ITIMER_REAL, &it, NULL);
  }
  
  /* Enable the software watchdog with the specified period in milliseconds. */
  void enableWatchdog(int period) {
      int min_period;
  
      if (server.watchdog_period == 0) {
          struct sigaction act;
  
          /* Watchdog was actually disabled, so we have to setup the signal
           * handler. */
          sigemptyset(&act.sa_mask);
          act.sa_flags = SA_ONSTACK | SA_SIGINFO;
          act.sa_sigaction = watchdogSignalHandler;
          sigaction(SIGALRM, &act, NULL);
      }
      /* If the configured period is smaller than twice the timer period, it is
       * too short for the software watchdog to work reliably. Fix it now
       * if needed. */
      min_period = (1000/server.hz)*2;
      if (period < min_period) period = min_period;
      watchdogScheduleSignal(period); /* Adjust the current timer. */
      server.watchdog_period = period;
  }
  
  /* Disable the software watchdog. */
  void disableWatchdog(void) {
      struct sigaction act;
      if (server.watchdog_period == 0) return; /* Already disabled. */
      watchdogScheduleSignal(0); /* Stop the current timer. */
  
      /* Set the signal handler to SIG_IGN, this will also remove pending
       * signals from the queue. */
      sigemptyset(&act.sa_mask);
      act.sa_flags = 0;
      act.sa_handler = SIG_IGN;
      sigaction(SIGALRM, &act, NULL);
      server.watchdog_period = 0;
  }
  